1. Field of the Invention
The present invention relates to a shell-and-tube heat exchanger type reactor filled with solid particles, and a method for producing (meth)acrylic acid and/or (meth)acrolein with the reactor.
2. Description of Related Art
Exothermic reactions such as an oxidation reaction in an industrial scale are performed with shell-and-tube reactors filled with catalyst and inert particles. Here, a heat medium exists among the reaction tubes in the shell. Such a reactor is used in the field of chemical industry for example methods for producing phthalic anhydride from o-xylene, acrolein and/or acrylic acid from propylene or propane, and methacrolein and/or methacrylic acid from isobutylene.
Evaluation of conditions of the shell-and tube reactor filled with catalyst particles has shown the selectivity and conversion of the prescribed products is affected remarkably by the temperature along with the reaction tubes. This temperature profile along with the axis is measured with thermometers. The thermometer is inserted into the reaction tube in the case of fixing the thermometer itself at a prescribed point, on the other hand, a protective tube for the thermometer is usually in advance inserted into the reaction tube and then the thermometer is inserted into the protective tube in the case of measuring the temperature profile while moving the thermometer along with the axis.
However, such a thermometer has a drawback that the thermometer occupies a certain volume in the reaction tube, hence a pressure profile along the axis is generally affected, and accordingly behavior for the pressure drop of the reaction tube in which the thermometer is placed is allowed to change. In the meantime, it is important for temperature measurement to be conducted at a representative reaction tube or more. The reaction process in the reaction tube with thermometers is required to coincide with the reaction process of the reaction tubes without thermometers.
JP-A-10-309457 describes, in order to fulfill such a problem and requirement, a shell-and tube reactor includes at least two same reaction tubes filled with solid particles and at least one reaction tube has a thermometer wherein both the ratio of the solid particle weight to free cross sectional area, per each reaction tube, and the pressure drops measured by means of an inert gas which is laterally introduced in proportion to the free cross section are coincidental, respectively, in the whole reaction tube.
In accordance with the above reactor, when the reaction tubes are filled in such a way that the ratio of the solid particle weight to the free sectional area and the pressure drop at the supplying a gas to the filled layer are identical, respectively, the temperature can be accurately measured even in the reaction tube in which the thermometer is inserted.
However, several kinds of solid particles with different particle sizes are necessary so as to fill the reaction tubes with smaller particles than the solid particles filled, for controlling the pressure drop.
Though sequential changes of pressure drops at solid particle layers in operations is very valuable for obtaining the conditions of solid particles, the same problem as the thermometer is found in the case of setting pressure measuring devices into the reaction tubes.